Contact lens having a hard center and soft, tough periphery

Claim 1

A wettable, transparent segmented contact lens for the eye consisting of fluorine-containing polymers and having a concavo-convex structure with the concave surface conforming substantially to the shape of the eye surface, a central segment defining an optical zone composed of a hard, stiff fluoropolymer of a Knoop hardness of at least 2.0 and a peripheral segment composed of a soft, tough fluoropolymer having a Clash-Berg torsion modulus in the range of about 95 to about 1000 lb/sq.in., a Shore Durometer (A) hardness of 90 or less, a tensile strength (break) of at least about 100 psi, an elongation (break) of at least about 160% and a tear strength of at least about 5 lb/linear inch; each segment having a refractive index in the range 1.30 to 1.40; the central segment being made from a fluoropolymer of the group consisting of polyperfluoro-2-methylene-4-methyl-1,3-dioxolane; poly(perfluoroalkylethyl methacrylate) of the monomeric formula ##EQU1## wherein n = 1, 2, 3, 4 and 5; copolymer of perfluoro-2-methylene-4-methyl-1,3-dioxolane and tetrafluoroethylene; copolymer of perfluoro-2-methylene-4-methyl-1,3-dioxolane and vinylidene fluoride; copolymer of hexafluoroacetone, tetrafluoroethylene and ethylene; copolymer of tetrafluoroethylene, perfluoro-2-methylene-4-methyl-1,3-dioxolane and perfluoro(propyl vinyl ether); copolymer of tetrafluoroethylene and perfluoro[2(2-fluorosulfonylethoxy)propyl vinyl ether] in which all the --SO 2 F groups have been converted to --SO 3 H groups; the same copolymer in which all the --SO 2 F groups have been converted to --SO 3 K groups; and the same copolymer in which all the --SO 2 F groups have been converted to --SO 3 NH 4 groups; and a copolymer of perfluoroalkylethyl methacrylates of the monomeric formula (A) ##EQU2## with one or more vinyl compounds wherein (A) is a mixture in which n = 1, 2, 3, 4, and 5 and wherein the content of vinyl compound is no more than 20% by weight; and the peripheral segment being made from a fluoropolymer of the group consisting of a copolymer of tetrafluoroethylene and perfluoro(methyl vinyl ether); the same copolymer plasticized with polyperfluoropropylene oxide oil; a copolymer of tetrafluoroethylene, perfluoro(methyl vinyl ether) and vinylidene fluoride; a copolymer of tetrafluoroethylene and perfluoro[2(2-fluorosulfonylethoxy)propyl vinyl ether]; a copolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene; and a copolymer of vinylidene fluoride and hexafluoropropylene.